Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$32.64	8.495%	$35.4128	$35.41	$35.40	$35.40
Purchase #2	$14.27	3.483%	$14.767	$14.77	$14.75	$14.80
Purchase #3	$172.97	7.200%	$185.4238	$185.42	$185.40	$185.40
Purchase #4	$169.72	8.173%	$183.5912	$183.59	$183.60	$183.60
Purchase #5	$51.56	6.448%	$54.8846	$54.88	$54.90	$54.90
Purchase #6	$100.32	4.674%	$105.009	$105.01	$105.00	$105.00
Purchase #7	$133.49	12.748%	$150.5073	$150.51	$150.50	$150.50
7 purchase totals =	$674.97		$729.5957	$729.59	$729.55	$729.60